An ink-jet recording apparatus has been known, which has a recording head for discharging ink as droplets onto recording paper to print an image thereon. The ink-jet recording apparatus is provided with at least an ink tank containing ink, to supply the ink from the ink tank to the recording head through an ink supply path. In an exemplar of the ink-jet recording apparatus, as disclosed for example in Japanese Laid-open Patent Application No. 2000-33715, the ink tank is placed above a head unit that consists of a recording head and other components.
The recording head is provided with a number of nozzles, pressure rooms and oscillation plates. The oscillation plates are disposed in correspondence with the respective pressure rooms, and are driven individually by piezoelectric elements. The oscillation of the oscillation plate causes a change in volume of the corresponding pressure room, which lets the nozzle discharge the ink droplets.
A problem in the conventional ink tank is that heat energy is generated from driving members of the recording head, like the piezoelectric elements, and the heat energy can heat the ink contained in the ink tank. With an increase in temperature of the ink, viscosity of the ink changes, which has a bad effect on discharging properties. Besides, the heated ink evaporates wastefully. This problem is not ignorable especially when the ink tank is attached to a line recording head which records a line of image at a time by discharging the ink from many nozzles. Because of the many nozzles, the line recording head generates much heat energy.